This is where a hobby such as learning to play a music instrument can be good for retirement. Other than the cost of the instrument itself and some learning materials, you alone decide how much or how little you want to spend. These days, you can learn on your own by purchasing a lesson package that is designed for that use. Guitar is ideal for this because you can learn to play the melody, harmony, and bass line all by yourself without having to sing at all if you don't want to.
For me, the acoustic guitar is a lifetime journey, with always something new to learn so I never get bored. It is a great instrument for apartment dwellers or those living in a condo, such as myself. You won't be loud enough to bother neighbors and the sound of an acoustic guitar is soothing, rather than the way a guitar is normally heard these days with all that distortion and slamming.
There are other inexpensive hobbies, such as reading. Used book stores and the library are excellent resources.
The problem I see with collecting something other than stamps or other items that a lot can fit in a small space, is the space that the objects take up. Also, every time you want to pursue that hobby, it involves finding something else to buy. I never understood collecting because I am the type who wants to do something, and with music or reading, you are doing something with the objects you have for the hobby.
Anyway, just a couple of thoughts...
Tony